you have not set the catsearch select list to have any options.
on the search page, select the catsaerch select list. in the property inspector, click the dynamic button and set the value to use the catID column of the rs_Categories recordset, and set the label to use the category Name column
add a static value with a blank value. Go into the code and make sure the value for the static option is set to value="":
<option value="">select a category</option>
the error you re getting is because you are adding this to a template, you should not be adding this to a template, but instead to the actual search and results pages.